添加JS

@@ -41,8 +41,7 @@ var date = {
             dayNum = 31;
 
         var select,
-            i,
-            isYearFour;
+            i;
 
         year = parseInt(year, 10);
         month = parseInt(month, 10);
@@ -65,8 +64,7 @@ var date = {
                 dayNum = 30;
             } else if (month === 2) {
                 dayNum = 28;
-                isYearFour = (year % 4) === 0;
-                if (isYearFour && (year % 100 !== 0 || year % 400 === 0)) {
+                if ((year % 4) === 0 && (year % 100 !== 0 || year % 400 === 0)) {
                     dayNum = 29;
                 }
             }